Method of series connecting heater elements for multiple electrode gun subassembly



Aug. 18, 1 970 v A. T. KURYLA METHOD OF SERIES CONNECTING HEATER ELEMENTS FOR MULTIPLE ELECTRODE GUN SUBASSEMBLY I Driginal Filed Nov. 1.

I ATTORNEY United States Patent 3,524,236 METHOD OF SERIES CONNECTING HEATER ELEMENTS FOR MULTIPLE ELECTRODE GUN SUBASSEMBLY Alan T. Kuryla, Geneva, N.Y., assignor to Sylvania Electric Products Inc., a corporation of Delaware Original application Nov. 1, 1966, Ser. No. 591,166, now Patent No. 3,396,298, dated Aug. 6, 1968. Divided and this application Mar. 18, 1968, Ser. No. 713,936

Int. Cl. H013 9/18, 9/36 US. Cl. 2925.16 3 Claims ABSTRACT OF THE DISCLOSURE CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 591,166, filed Nov. 1, 1966, now Pat. No. 3,396,298, assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates generally to electron-guns and more particularly to improved means for providing a series connection of the heater elements in tubes having multiple electron-guns. Although having general application, the invention finds particular utility in color picture tubes of the three-gun type.

In multiple electron-gun cathode ray tubes, the heater current is supplied to the tube by way of two stem-leads which are in turn connected to the heater elements of the respective electron-guns. According to presently accepted practice, a number of straps are mounted on insulating support rods within the tube and each strap provides a connection between the ends of heater elements in adjacent electron-guns or between one end of a heater element and an input stem-lead. Because of the number of straps involved, the mounting operation is relatively timeconsuming and great care must be exercised in the mounting of the straps to assure proper alignment of the straps with the location of the ends of the heater elements. If a strap is improperly mounted, the heater element connected thereto may be distorted and thereby affect the operating characteristics of its associated electron-gun. It is also possible that an improper mounting may result in a shorting of the heater element. These difficulties are particularly troublesome in color television picture tubes where the failure of any one electron-gun effectively renders the tube inoperative.

OBJECTS AND SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a simplified, more reliable and economical heater element mounting method for multiple electron-gun cathode ray tubes.

The foregoing and other objects and advantages are achieved in one aspect of the invention which utilizes a single preformed connecting strap which can be positively placed in and fastened to the insulating support rods of 3,524,236 Patented Aug. 18, 1970 thereby eifecting the desired series connection of the heater elements.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the accompanying drawings, in which:

FIG. 1 is a partial perspective view of a three electrongun structure embodying the invention;

FIGS. 2 and 3 are end elevation views of alternate embodiments of the invention for three electron-gun structures;

FIG. 4 is a partial side view of a preformed heater element connecting straps according to the invention;

FIG. 5 is a partial perspective view of an alternate embodiment of a preformed heater element connecting strap according to the invention; and

FIG. 6 is a partial end view of an alternate configura tion of a preformed heater element connecting strap according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For simplicity and ease of understanding, the invention will be described in connection with a three-gun structure, such as used in a color picture tube. However, it will be apparent that the disclosed concept is applicable to any multiple electron-gun structure.

Referring to FIG. 1, there is shown the envelope 11 of a tube within which are contained three insulating support rods 13, 14 and 15. Mounted in the envelope 11 are cylindrical cathode elements 17, 18 and 19 within each of which is contained a respective heater element, only the ends of which are shown. The cylindrical cathode elements are connected to the insulating support rods 13, 14 and 15 by suitable cathode mounting straps (not shown). The ends of the heater elements are supported by four connecting straps 23, 24, 25 and 26, which are, in turn, connected to the support rods 13, 14 and 15 by mounting posts 29, 30, 31 and 32, respectively. Connecting members 33 and 35 provide connections between straps 26 and 23, respectively, and the heater element stem-leads (not shown). While the connecting straps 23 26 appear as separate elements in the completed structure, they are derived from a single preformed strap to be later described.

FIG. 2 shows the manner in which the invention provides a supporting series connection for the heater elements 41, 42 and 43 of cathodes 45, 46 and 47, respectively, in a three electron-gun structure. A preformed connecting strap 49 having three elongated protuberances 51, 52 and 53, suitably spaced along its perimeter, is mounted in the gun structure by affixing the strap 49 to mounting posts 55, 56, 57 and 58 which are embedded in glass support rods 60, 61 and 62. After the connecting strap 49 is thus firmly mounted in the gun structure, the center portions of the elongated protuberances 51-53 are cut-out to provide discontinuities in the connecting strap. The cut-out of the center portion of the elongated pro tuberances can be done in any conventional manner. For example, it can be performed manually such as by an operator using a pair of diagonal pliers or metal cutters. Furthermore, because of the close tolerances possible, the cut-out operation could be fully automated. The ends of the heater elements 41,42 and 43 are connected to the elongated protuberances 51, 52 and 53, respectively, such that each heater element is connected across the discontinuity in its respective elongated protuberance, thereby forming the desired series connection of the heater elements in the gun structure. Leads 64 and 65 aflixed, respectively, to mounting posts 57 and 58 are connected to the input stem-leads (not shown) supplying heater current. t

The advantages of providing series heaters connections in this manner will be readily apparent to those skilled in the art. Since the single connecting strap is preformed, its dimensions can be closely controlled such that when placed in the gun structure, the elongated protuberances are in positive registration with the cathode elements, thereby permitting accurate controlled placement of the heater element and substantially reducing the possibility of gun failure resulting from a shorted or distorted heater element. Furthermore, because the dimensions of the connecting strap 49 are controlled, thereby assuring positive placement with proper registration in the gun structure, the steps of mounting the connecting strap in the gun structure and forming the series connection are less likely to result in faults due to human error.

It will be appreciated that the connecting strap can be formed in a variety of shapes, depending upon particular requirements or preferences. For example, the preformed connecting strap 79 shown in FIG. 3 is generally triangular in shape with the side of the strap connected via mounting posts 85, 86, 87 and 88 to the glass support rods 90, 91 and 92. The corners 95, 96 and 97 of the strap 79 are flattened to provide proper registration of the strap over the cathode elements and to facilitate the location of the cut-outs necessary to provide the discontinuities across which the heater elements 101, 102 and 103, respectively, are connected.

As illustrated in FIG. 4, it may be desirable to cut out a portion 107 in the center of the elongated protuberance 109 of the strap 110 during the forming operation. Then, when the strap 110 is mounted in the gun structure, less cutting force is required to remove the remaining center 111 of the elongated protuberance 109 in providing the discontinuity across which the heater element is to be connected, and the possibility of distorting the strap 110 during the cutting operation is reduced.

According to a further embodiment of the invention, as disclosed in FIG. 5, the preformed connecting strap 115 may have one or more mounting tabs 117 suitably positioned along one edge such that, when placed in the electron-gun structure, the mounting tab is in registration with a respective mounting post 119 which is embedded in a glass support rod 121. Utilizing this configuration, the mounting tabs will support the connecting strap in a proper position in the electron-gun structure prior to the welding operation which secures the connecting strap to the mounting posts.

As shown in FIG. 6, the elongated protuberance 125 may be formed to extend inward from the circumference of the connecting strap 127. Also, the connecting strap 127 may be constructed from material having a substantially circular cross section, i.e. wire, rather than from ribbon stock material as previously shown. The particular choice of strap material and strap configuration may, therefore, vary depending upon design limitations and structural requirements without departing from the scope of the present invention.

Thus, there is provided improved means for interconnecting the heater elements in a multiple-electron gun structure. The utilization of the preformed connecting strap having controlled dimensions assures the proper mounting in the gun structure in registration with the cathode elements, thereby facilitating the correct placement of the heater elements within the cathode elements. Since the possibility of human error is substantially reduced, the resultant structure is inherently more reliable and less likely to fail. Also, the controlled dimensions of the preformed connecting strap, make it possible to automate part of the heater element mounting process. For example, by machine process it is now possible to insert the preformed connecting strap in the electron gun subassembly, weld the strap to the mounting posts and cut out the desired portions of the elongated protuberances prior to the insertion of the cathode heater elements, thereby providing a more economical gun structure.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In a multiple electron-gun subassembly including a plurality of insulating support rods and a plurality of cathode elements each having a heater element, a method for connecting said plurality of heater elements in series comprising the steps of:

preforming a strap of conducting material to have a plurality of elongated protuberances, each of said protuberances defining an area to be subsequently removed;

securing said preformed strap of conducting material to said plurality of insulating support rods such that each of said elongated protuberances is supported in a fixed spatial relation to one of said cathode elements;

removing the aforementioned removable area of each of said plurality of elongated protuberances to provide a discontinuity therein; and

connecting each of said heater elements across its respective discontinuity.

2. The invention according to claim 1 wherein the step of removing the aforementioned removable area of each of said plurality of elongated protuberances occurs after said connecting each of said heater elements to thereby affect the series connection of said plurality of heater elements.

3. The invention according to claim 1 wherein the step of preforming a strap of conducting material to have a plurality of elongated protuberances additionally comprises preforming a plurality of mounting tabs suitably spaced along said strap and wherein the step of securing said preformed strap of conducting material to said plurality of insulating support rods consists of attaching said plurality of mounting tabs respectively to said plurality of insulating support rods.

References Cited UNITED STATES PATENTS 2,486,064 10/1949 Saucet 2925.11 XR 3,387,166 6/1968 Kraner et a1. 29-25.16 XR 3,391,298 7/1968 Dorota 2925.16= XR JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US. Cl. X.R. 2925.15 

